.box {
  background-image: url(../img/bj.png);
  background-repeat: no-repeat;
  background-size: 100%;
  height: calc(100vw * 3128 / 1345);
}
.cover {
  background-color: rgba(0, 0, 0, 0.5);
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  display: none;
  align-items: center;
  justify-content: center;
}
